Do believers sin because they still have a sinful nature?

Q. I’ve heard that believers in Jesus still have a “sinful nature” or a desire within them towards sin. The book we’re using in our Bible study says that “because of this sinful nature, we commit actual sins, even as believers.”
But I think we can’t blame all our sinning on the sinful nature. Sometimes we can sin by our will, when it’s in opposition to the divine will. I think free will is free, but when it exceeds the will of God, which it can because it’s free, it approaches autonomy instead. If we head in this direction, in direct opposition with God’s will, it’s sin. 
Some might use this to justify their position that Jesus could not have sinned, since he did not have a sinful nature. But he did have free will. I think it was in this sense that Jesus was truly tempted but praise God, he was sinless and our perfect sacrifice.
Adam and Eve didn’t have a sinful nature, but they sinned nevertheless. Satan tempted Eve with the same desire for autonomy and it worked. He told her that “your eyes will be opened, and you will be like God.” Perhaps Lucifer’s sin in the first place was that he went too far with free will in his desire for autonomy. What do you think?

I understand the question you are asking to be this: how can believers in Jesus, who are regenerated through faith and so are a new creation, still sin? Is it only because, in addition to having a redeemed nature, they still have a sinful nature that leads them into sin? Or do they also sin because they have free will and sometimes misuse it by seeking autonomy and going beyond the will of God? To show that the sinful nature is not the only cause of sin, you offer the examples of Adam and Eve, who did not have a sinful nature but who nevertheless sinned, and of Jesus, who also did not have a sinful nature but who, you suggest, could have sinned if he had chosen by his free will not to obey God.

Let me take up your points one at a time.

First, personally I do not think that believers in Jesus have two natures, a redeemed nature and a sinful nature. This idea was responsible for the translation in the 1984 New International Version (NIV) of the Greek term sarx as “the sinful nature” in many contexts. That translation itself further popularized the idea. But you may be aware that in the 2011 update to the NIV, in virtually all of those contexts the translation was changed to “the flesh.” That reflects a change in understanding on the part of the committee of some 15 established biblical scholars who are responsible for the NIV. They now consider the term sarx in these contexts to refer to an ingrained pattern of life that may carry forward from the time before a person became a believer and that is reinforced by the “world,” meaning the system of interests on this earth that are arrayed against God.

The repeated admonitions in Paul’s epistles are to live “not according to the flesh” but “according to the Spirit,” and to “put off” the “old man” (representing that former way of life). Paul says in Romans, “Do not conform to the pattern of this world, but be transformed by the renewing of your mind.” I don’t think he would speak that way if believers had a sinful nature that inevitably led them to sin. The way Paul speaks indicates instead to me that believers, as regenerate persons empowered and guided by the Holy Spirit, have the capacity to learn a new way of life and to live it out victoriously. Nothing in them requires them to sin. They just need to unlearn their old ways and learn new ways, standing against the surrounding way of life. Inner healing may be necessary in order for them to become free of some entrenched patterns.

Regarding Jesus, you are in agreement with the consensus of traditional Christian interpretation when you say that he could have sinned. The historic debate was whether Jesus was “not able to sin” (non posse peccare) or “able not to sin” (posse non peccare), and it was resolved in favor of the latter position. Jesus was able not to sin because in his incarnation he was completely yielded to his Father’s will and completely dependent on the empowering of the Holy Spirit. In that way Jesus sets an example of every one of his followers. If we too are completely yielded to God’s will and completely dependent on the Holy Spirit, we will not sin.

You recognize that what I have said to this point supports your suggestion that sin may come from the misuse of free will rather than from a sinful nature within us that compels us to sin. Before we are regenerate, we are in bondage to sin. Sin has power over us that we are not strong enough to break, despite our best intentions. But once we are regenerate, there is a greater power within us, the Holy Spirit, who makes us “able not to sin.” As Paul also wrote in Romans, “The law of the Spirit of life in Christ Jesus has set you free from the law of sin and death.” But we must use our will to choose to do God’s will. In this Jesus also sets an example for believers. As the book of Hebrews says, when Jesus came to earth, he said, in effect, “Here I am, I have come to do your will.”

I think there is a process of discovery that we go through as believers. Previously we were fending for ourselves, perhaps thinking of God as someone who was distant and uncaring or who was angry and hostile. Once we are restored to fellowship with God through faith in Jesus, we really do need to be “transformed by the renewing of our minds” and recognize that God loves us more than we could ever imagine. What God wants for us will make us happy and flourishing and a blessing to all those around us. So we should gladly and eagerly say to God, “Please show me your will so I can do it!” Ultimately we will be motivated in this by our love for God, which will be prompted by our growing recognition of how much God loves us.

Augustine, who participated prominently in the discussion of “not able to sin” versus “able not to sin,” also once said, “Love God, and do what you will.” In other words, nothing sinful can come from pure love for God. So rather than trying to sort out which of two natures an action might reflect (since there probably aren’t two natures anyway), or even whether free will is shading over into autonomy, I think we should just try to open our eyes to see how much God loves us. The evidence is everywhere. We will love God in return, and consequently we will want—we will will—to do his will.